MEETING THE CHALLENGES OF IN-WATER DESIGN AND CONSTRUCTION

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Miranda Stokes
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1 1 May 2015 MEETING THE CHALLENGES OF IN-WATER DESIGN AND CONSTRUCTION JAMIE DUBOIS, P.E. PROJECT ENGINEER WATER DIVISION

2 AGENDA 1. Program and Project Background 2. River Hydrology and Intake Siting 3. Construction 2

3 PROGRAM AND PROJECT BACKGROUND 3

P R O G R A M A N D P R O J E C T B A C K G R O U N D DEVELOPMENT OF THE PARTNERSHIP August 2008 Cities of Lake Oswego and Tigard enter partnership agreement to share drinking water resources and

4 P R O G R A M A N D P R O J E C T B A C K G R O U N D DEVELOPMENT OF THE PARTNERSHIP August 2008 Cities of Lake Oswego and Tigard enter partnership agreement to share drinking water resources and costs. Develop full use of Lake Oswego s existing Clackamas River water rights to supply 38 MGD. Tigard customers gain a long-term, affordable drinking water source. Lake Oswego spreads the cost for needed upgrades among a larger base of rate payers. 4

5 P R O G R A M A N D P R O J E C T B A C K G R O U N D GEOGRAPHY Tigard Buys water from Portland and Lake Oswego Lake Oswego Currently Utilizes 16.5 MGD of 38 MGD rights Project Site 5

P R O G R A M A N D P R O J E C T B A C K G R O U N D Water

ALL CAPS REVENUE BY BUSINESS 9% Federal Services 37% B&V Energy

Water Pipeline Upgraded Water Treatment Plant Treated Finished

*Designed by B&V NOTE: Sidebar is optional and should only be

6 P R O G R A M A N D P R O J E C T B A C K G R O U N D Water System Improvements KEEP TITLES SHORT 2 LINES MAX; TITLE TEXT IS ALL CAPS REVENUE BY BUSINESS 9% Federal Services 37% B&V Energy 27 February 2014 New River Intake Pump Station* Untreated Raw Water Pipeline Upgraded Water Treatment Plant Treated Finished Water Pipeline New Waluga Reservoir* New Bonita Pump Station* *Designed by B&V NOTE: Sidebar is optional and should only be used in conjunction with an AGENDA and DIVIDER slides. Sidebar mimics Divider only. 22% Telecom 4% Management Consulting 28% B&V Water Use this space to drive home message of the slide utilizing Cambria font at size 22 6

P R O G R A M A N D P R O J E C T B A C K G R O U N D EXISTING INTAKE PUMP STATION ISSUES Vulnerability to withstand seismic events. Maximum pumping capacity of 16.5 MGD Firm capacity of 11.

7 P R O G R A M A N D P R O J E C T B A C K G R O U N D EXISTING INTAKE PUMP STATION ISSUES Vulnerability to withstand seismic events. Maximum pumping capacity of 16.5 MGD Firm capacity of 11.7 MGD. Insufficient pump intake and impeller submergence during low river/peak demand season. Poor sweeping velocity to carry algae mats and debris downstream. Existing Intake built in

8 RIVER HYDROLOGY AND INTAKE SITING 8

9 R I V E R H Y D R O L O G Y A N D I N T A K E S I T I N G RIPS SITE ALTERNATIVES River hydrology and intake siting 9

10 R I V E R H Y D R O L O G Y A N D I N T A K E S I T I N G Monthly 5%, 50% (Median), and 95% exceedance flows for the Clackamas River near Oregon City 10

11 R I V E R H Y D R O L O G Y A N D I N T A K E S I T I N G CLACKAMAS RIVER HYDROLOGY River hydrology and intake siting Intake located at upper end of pool with riffles leading into and out of the pool. Bank at intake is soft rock that tends to be scoured clean Rocky outcrop of hard rock and boulders 100 ft upstream 11

12 R I V E R H Y D R O L O G Y A N D I N T A K E S I T I N G EXISTING BATHYMETRY River hydrology and intake siting Extent and bathymetry of model developed to estimate 2D flow conditions 12

R I V E R H Y D R O L O G Y A N D I N T A K E S I T I N G NEW BATHYMETRY NEAR INTAKE River hydrology and intake siting Currently an eddy occurs during various low flow conditions resulting

13 R I V E R H Y D R O L O G Y A N D I N T A K E S I T I N G NEW BATHYMETRY NEAR INTAKE River hydrology and intake siting Currently an eddy occurs during various low flow conditions resulting in poor sweeping velocity across the intake fish screens. Channel excavated upstream of the intake to funnel flow toward screens. Channel required excavation of 1,600 cubic yards of rock. 13

14 R I V E R H Y D R O L O G Y A N D I N T A K E S I T I N G RIVER MODELING Summary of flow and velocity conditions modeled at the intake: River hydrology and intake siting 14

15 R I V E R H Y D R O L O G Y A N D I N T A K E S I T I N G RIVER MODELING River hydrology and intake siting Eddy Run 1: Existing bathymetry, low flow, maximum withdrawal (Sweeping Velocity = -0.2 ft/sec) 15

16 R I V E R H Y D R O L O G Y A N D I N T A K E S I T I N G RIVER MODELING River hydrology and intake siting Run 3: New bathymetry, low flow, maximum withdrawal (Sweeping Velocity = 0.51 ft/sec) 16

17 CONSTRUCTION 17

18 IN WATER WORK PERIOD FOR CLACKAMAS RIVER In-Water Work Period (IWWP): July 15 th August 31 st Avoid vulnerable life stages (including migration, spawning, and rearing) of important fish species. Anadromous fish that live part or the majority of their lives in in saltwater, but return to fresh water to spawn. IWWP dictated by following fish species: Chinook (King) Salmon fall and spring runs Coho (Silver) Salmon Steelhead summer and winter runs Cutthroat Trout 18

19 CONSTRUCTION CHALLENGES Site access is extremely limited In-Water Work Period (IWWP): July 15 th August 31 st General Construction Schedule: 1 st IWWP (2013) construct work bridge and cofferdam. Excavate within cofferdam and construct RIPS structure. 2 nd IWWP (2014) remove cofferdam, construct channelization. Startup and testing. 3 rd IWWP (2015) demolish existing RIPS. 19